Brazil’s presidential election is heading for a decisive October 25 runoff after right-wing Senator Flávio Bolsonaro unexpectedly finished ahead of incumbent Luiz Inácio Lula da Silva in the first round, giving the Bolsonaro movement fresh momentum while leaving the final outcome far from settled.

With 99.99% of the votes counted, Bolsonaro won 56.1 million votes, or 47.03% of valid ballots, while Lula secured 53.9 million votes, or 45.16%, according to Brazil’s Superior Electoral Court. Neither candidate crossed the 50% threshold required to win outright. The first round recorded 125.27 million valid votes, along with 2.30 million blank ballots and 3.67 million invalid votes.

The result overturned the expectations of several pre-election polls, which generally showed Lula with a narrow advantage going into voting. It also means that Brazil’s deeply polarised electorate will now be asked to choose between an 80-year-old incumbent seeking a fourth non-consecutive term and a 45-year-old political heir to former President Jair Bolsonaro.

The runoff will be fought over voters who backed the other 10 presidential candidates, as well as millions who may be dissatisfied with both leading contenders.

Bolsonaro turns a polling deficit into a political advantage

Flávio Bolsonaro’s first-round performance is significant because it gives the right-wing candidate the psychological advantage of entering the runoff as the vote leader.

Political analyst Rafael Favetti told Reuters that the result could represent a “protest vote” against Lula that moved toward Bolsonaro earlier than expected. “The protest vote foreshadows what is to come in the run-off,” Favetti said, warning that Bolsonaro may have already captured some voters who otherwise would have shifted to him only in the second round.

That creates a complicated calculation for the Bolsonaro campaign. The first-round result demonstrates that he can mobilise voters beyond his core supporters, but it may also mean that some of his potential second-round gains have already been exhausted.

Lula acknowledged that the result was unexpected but sought to project confidence.

“I admit, I was convinced I would win in the first round. The game is about to start. We are in extra time. In extra time, we will win over the Brazilian people,” Lula said after the results.

The former union leader now faces the challenge of converting his incumbency into a positive argument while preventing the runoff from becoming a simple referendum on his government.

Crime, living costs and economic sentiment are likely to dominate that contest. Bolsonaro has campaigned heavily on public security and political change, while Lula has sought to frame the election as a defence of democracy, social programmes and Brazilian sovereignty.

The contest is also likely to remain entangled with former President Jair Bolsonaro, who is serving a 27-year sentence after being convicted of plotting to overturn the 2022 election result. Flávio has pledged to seek an amnesty for his father if elected.

The bigger warning for Lula is the strength of Brazil’s right

The presidential result cannot be viewed in isolation. The first round also produced a strong performance by Bolsonaro-aligned candidates in congressional and state races, suggesting that the political infrastructure behind the Bolsonaro movement remains intact despite Jair Bolsonaro’s imprisonment and exclusion from the presidential race.

The Liberal Party, or PL, was on course to become the largest force in the Chamber of Deputies and also made gains in the Senate. Bolsonaro’s stepmother, former first lady Michelle Bolsonaro, won a Senate seat in the Federal District, while his brother Carlos Bolsonaro was elected to the Senate in Santa Catarina.

“The fact that far-right candidates for the legislature have exceeded all expectations suggests a deeper popular grounding for the bolsonarista project than many expected,” Andre Pagliarini, an assistant professor of history and international studies at Louisiana State University, told Al Jazeera.

“Millions of Brazilians right now evidently feel the right best reflects their values and vision for the future,” he said.

That congressional shift could become crucial after October 25. Even if Lula wins another term, a stronger conservative legislature could make it harder for his administration to advance legislation. A Bolsonaro presidency, by contrast, would inherit a political environment more receptive to the right’s agenda.

The other major uncertainty is the electorate that rejected both leading candidates in the first round. Ronaldo Caiado and Renan Santos, who together received about 5.3 million votes, have previously indicated they would not endorse either candidate. Their supporters therefore cannot automatically be treated as Bolsonaro voters.

Turnout could also become decisive. Voting is compulsory for Brazilians aged 18 to 70, although exemptions apply to some groups, including people over 70. A large number of voters who are legally required to participate may still be reluctant to choose either candidate.

The US factor adds another layer to the runoff. President Donald Trump has maintained political ties with the Bolsonaro family, while Lula has accused Washington of attempting to influence Brazil’s election. The Trump administration has denied seeking to interfere, but US tariffs, sanctions and diplomatic pressure have made Brazilian sovereignty a central campaign issue.

The October 25 runoff will therefore be about more than Lula versus Flávio Bolsonaro. It will test whether the first-round result reflects a durable rightward shift in Brazil or a temporary consolidation of voters determined to prevent Lula from securing another term.

For Lula, the immediate task is to turn the two-point deficit into a case for continuity. For Bolsonaro, it is to convert a stronger-than-expected first round into a majority without alienating voters who supported other candidates.

The first round has given Bolsonaro momentum. It has not, however, given him the presidency.